Fiorenza Micheli, a professor of marine science at Stanford University and co-director of the school’s Center for Ocean Solutions, said kelp forests are a sentinel for the health of the oceans.

“We are seeing change that is happening very rapidly and on a very large scale,” she said, “and it’s affecting this ecosystem — and very little is being done.”

Studies have predicted that unless the world stops dumping increasing amounts of CO2 into the atmosphere, marine heat waves will become the “new normal” by the end of this century. Micheli called for better monitoring and more research to identify heat-resistant types of kelp that can be used for restoration.

Off the coast of Northern California, 90% of kelp has died off in the past five years, which threatens many species of commercially important fish. Micheli said she believes the United States must join other countries to tackle climate change, the ultimate driver of this problem.

“Global action in addressing the ultimate cause of this problem — that is the most important part of this,” she said. “Everything else is really just a way of buying some time.”

She said California, Oregon and Washington state need to coordinate efforts to restore damaged kelp forests, remove some of the sea urchins that are overfeeding on the kelp, and protect otters and other species that prey on sea urchins.